Qunio Electronics introduces you: the structural characteristics of aluminum electrolytic capacitors
Article Source：QUNIO ELECTRONICS
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issuing time：2019-04-09
The aluminum shell and the rubber cover are sealed to form an electrolytic capacitor. Compared with other types of capacitors, aluminum electrolytic capacitors exhibit the following obvious features in structure:
1. The working medium of the aluminum electrolytic capacitor is to form a very thin layer of aluminum oxide (Al2O3) on the surface of the aluminum foil by anodizing. The oxide dielectric layer and the anode of the capacitor are combined into a complete system. Dependent, not independent of each other; we usually refer to capacitors whose electrodes and dielectrics are independent of each other.
2. The anode of the aluminum electrolytic capacitor is an aluminum foil on the surface of the Al2O3 dielectric layer. The cathode is not the negative foil that we are accustomed to, but the electrolyte of the capacitor.
3. The negative foil plays an electrical role in the electrolytic capacitor because the electrolyte as the cathode of the electrolytic capacitor cannot be directly connected to the external circuit, and the electrical path must be formed by the other metal electrode and other parts of the circuit.
4. The anode aluminum foil and the cathode aluminum foil of the aluminum electrolytic capacitor are usually corroded aluminum foil, and the actual surface area is much larger than the apparent surface area, which is also a reason why the aluminum electrolytic capacitor usually has a large electric capacity. Due to the use of aluminum foil with numerous micro-etched holes, a liquid electrolyte is usually required to make more efficient use of its actual electrode area.
5. Since the dielectric oxide film of the aluminum electrolytic capacitor is obtained by anodizing, and its thickness is proportional to the voltage applied by the anodization, in principle, the dielectric layer thickness of the aluminum electrolytic capacitor can be artificially accurate. control.
